The inventive concepts relate to a semiconductor memory device, and more particularly, to a three-dimensional semiconductor memory device.
Semiconductor devices that offer high performance and which are low in cost to manufacture are in demand. In this respect, the integration density of semiconductor devices is an important factor in determining product price. Therefore, highly integrated semiconductor devices are increasingly sought after in particular. The integration density of typical two-dimensional or planar semiconductor memory devices is primarily determined by the area occupied by a unit memory cell constitute by fine patterns. Accordingly, the degree to which typical two-dimensional or planar semiconductor memory devices can be integrated is greatly influenced by the level of technology for forming fine patterns. However, extremely expensive processing equipment is required to form pattern fineness and thus equipment costs set a practical limitation on increasing the integration density of the two-dimensional or planar semiconductor memory devices. Therefore, three-dimensional semiconductor memory devices having three-dimensionally arranged memory cells have been proposed.